Synthesis and new rearrangements of 4-isoxazolin-4,5-dicarboxylic acid derivatives |
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Authors: | Necdet Co?kun,Aylin Ö ztü rk |
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Affiliation: | Uluda? University, Department of Chemistry, 16059 Bursa, Turkey |
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Abstract: | Acyclic nitrones react with dimethyl acetylenedicarboxylate (DMAD) to give stable isoxazolines, from which the ones that contain electron-donating aromatic rings at the C3 position (R1) were shown to undergo unprecedented fragmentation at room temperature, giving the R1-aldehyde and inseparable product mixtures, probably due to the formation of highly reactive species such as iminocarbenes. Attempts to convert the isoxazolines to the corresponding stable azomethine ylides, by refluxing in toluene, again led to the same product mixtures as above (e.g., the room temperature decomposition). Isoxazolines when reacted with methoxide at room temperature afforded highly functionalised diastereomeric mixtures. Also, isoxazolines, when reacted with propylamine, gave the corresponding amides regioselectively, all of which were more stable than the parent isoxazolines. |
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Keywords: | Dipolar cycloaddition Nitrones Acyclic azomethine ylides 4-Isoxazolines Pyrrole derivative 1H-Pyrrole-3-carboxylic acid methyl ester Rearrangement |
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